JP2871549B2 - Cleaning blade for electrophotographic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning blade for an electrophotographic apparatus having a long-term stable cleaning property in a wide temperature range.

[0002]

2. Description of the Related Art An electrophotographic apparatus has a photoconductor provided with a photoconductor layer on a surface thereof. In operation, an outer peripheral surface of the photoconductor is uniformly charged. An electrostatic latent image is formed by exposing the outer peripheral surface of the electrostatic latent image via a copied image, and a toner image is formed by attaching toner to the electrostatic latent image, and the toner image is transferred and fixed on paper or the like. It is.

In this process, since a part of the toner remains on the outer periphery of the photoreceptor after the transfer, it is necessary to remove the residual toner. Such removal of the toner is performed by a cleaning blade. The cleaning blade is usually formed of a support member made of a metal plate, a blade member made of an elastic body, and an adhesive layer for attaching the blade member to the support member.

Since the blade member contacts the photoreceptor and removes residual toner, the blade member causes less damage to the photoreceptor and has an appropriate pressing force during cleaning.
It is required to have excellent wear resistance. Conventionally, for such a blade member, an elastic body made of a polyurethane elastomer having a JIS A hardness of 65 to 80 has been used as having excellent mechanical strength and abrasion resistance.

[0005]

By the way, when the cleaning blade is used, a chattering sound (squeal) may occur. It has been found that this chattering sound is correlated with the rebound resilience, and is more likely to occur when the rebound resilience exceeds 75%.

Usually, an electrophotographic apparatus is used in an environment of 5 to 40 ° C., and the temperature in the apparatus is 5 to 60 ° C. At this time, the blade member is provided with the internal temperature, particularly 60 ° C.
Is required to be not more than 75%.

The excellent mechanical strength and abrasion resistance of the polyurethane elastomer depend on the strong physical bond of the urethane bond. However, on the other hand, since the physical coupling is dominant, the rebound resilience has a large temperature dependency, and it is difficult to control the rebound resilience to 75% or less over the entire temperature in the device.

The temperature dependency of the characteristics of such a blade member is described in, for example, JP-A-59-30574.
A cleaning blade for an electrophotographic copying machine made of a polyurethane elastomer obtained by using a polycaprolactone ester polyol having an average molecular weight of 1,000 to 4,000 as a polyol component provides stability against temperature changes, thermal durability, and good long-term cleaning performance. It is disclosed that an effect can be obtained.

However, the disclosed electrophotographic cleaning blade is not different from the prior art in that it relies on the above-mentioned strong physical bonding, and rebounds particularly in a high temperature range (50 to 60 ° C.) of the inside temperature of the apparatus. It was difficult to control the elasticity to 75% or less and suppress the generation of chattering noise.

In view of the above situation, the present invention has been made through a series of studies on the viscoelastic behavior of the blade member, and can control the rebound resilience in the above-mentioned device temperature range to 75% or less.
It is an object of the present invention to provide a cleaning blade for an electrophotographic apparatus having a stable cleaning property in the apparatus temperature range.

[0011]

The gist of the present invention is to provide a cleaning blade for an electrophotographic apparatus comprising a blade member, a support member, and an adhesive layer, wherein the blade member comprises a polyol having a molecular weight of 700 or less; 4500
The present invention resides in a polyurethane elastomer having a mixture with the above polyol as a polyol component. Hereinafter, the present invention will be described in detail.

The polyurethane elastomer used in the present invention comprises a polyol having a molecular weight of 700 or less and a polyol having a molecular weight of 45 or less.
A mixture with 00 or more polyols is used as a polyol component.

In the present invention, the polyol having a molecular weight of 700 or less and the polyol having a molecular weight of 4500 or more are mixed and a low molecular weight polyol is interposed between the long chains of the high molecular weight polyol to thereby diversify the structure. Therefore, the number of relaxation mechanisms is greatly increased, and the blade member made of the polyurethane elastomer has a small temperature dependency in a wide temperature range, and the resilience at a high temperature can be controlled.

The molecular weight of the low molecular weight polyol is larger than 700, or the molecular weight of the high molecular weight polyol is 450
When it is less than 0, the rebound resilience at 60 ° C. of the obtained polyurethane elastomer becomes greater than 75%,
When used as a cleaning blade, the possibility of generation of chattering noise (squeal) increases. Therefore, the polyurethane elastomer forming the blade member of the cleaning blade of the present invention comprises a low molecular weight polyol having a molecular weight of 700 or less and a high molecular weight polyol having a molecular weight of 4500 or more. It is limited to a mixture containing a polyol with a molecular weight polyol. The molecular weight of the polyol is (molecular weight of polyol) = (56
100) / (hydroxyl value) × (number of functional groups of polyol).

The high molecular weight polyol and low molecular weight polyol include, for example, polyethylene adipate,
Polyester adipates such as polybutylene adipate, polyhexane adipate, and polycaprolactone are used, and the same high molecular weight polyol and low molecular weight polyol are preferably used, but may be different.

The mixing amount of the low molecular weight polyol having a molecular weight of 700 or less with respect to the high molecular weight polyol having a molecular weight of 4500 or more is 5 to 30% by weight, preferably 10 to 25% by weight.

The cleaning blade for an electrophotographic apparatus according to the present invention is prepared by reacting a polyisocyanate with the above-mentioned mixed polyol of a polyol having a molecular weight of 700 or less and a polyol having a molecular weight of 4500 or more to prepare a prepolymer.
A reaction solution to which a curing agent (also referred to as a cross-linking agent) is added is poured into a mold and thermally cured by centrifugal molding or the like to form a thickness of 2 mm.
The front and rear sheets made of polyurethane elastomer are cut to a predetermined size to obtain a blade member, which is adhered to a support member to obtain a blade member. In addition, before the reaction liquid is injected into the mold, a support member that has been subjected to an adhesive treatment may be disposed in the mold, and the injected reaction liquid may be thermoset and bonded and integrated at the same time.

The polyisocyanate for forming a prepolymer by reacting with the mixed polyol is not particularly limited, but 4,4'-diphenylmethane diisocyanate (hereinafter referred to as MDI) is preferably used. Also,
The curing agent that is mixed with the prepolymer to cause a thermosetting reaction is not particularly limited, but includes 1,4-butanediol (hereinafter, referred to as 14BG), 1,6-hexanediol (hereinafter, referred to as 16HG), and trimethylolpropane (hereinafter, referred to as 16M). Hereinafter referred to as TMP), especially 14B
A mixture of G and TMP (hereinafter referred to as 14BG / TMP) and a mixture of 16HG, 14BG and TMP are preferably used.

As the adhesive for integrating the blade member and the support member, a phenol-based or epoxy-based liquid adhesive or a hot-melt adhesive such as a dimer acid-based, ethylene vinyl acetate-based, or polyurethane-based adhesive is preferably used. As the support member, a plate such as a surface-treated steel plate, stainless steel, or aluminum is preferably used.

[0020]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 Synthesis of polyethylene adipate ester
Parts by weight, ethylene glycol 1841 parts by weight, 1
The dehydration condensation reaction was performed at 80 ° C. for 24 hours. The hydroxyl value of the obtained polyol was 22.5 KOH mg / g, and the acid value was 0.8 KOH mg / g. The molecular weight was 4987. Next, as a synthesis of a low molecular weight polyol, 371 parts by weight of adipic acid and 220 parts by weight of ethylene glycol were charged and a dehydration reaction was performed at 180 ° C. for 5 hours. The hydroxyl value of the obtained polyol was 225 KOH mg / g, and the acid value was 0.3 KOH mg / g. According to the above formula, the molecular weight of this polyol was 499.

Synthesis of Prepolymer The low molecular weight component and the high molecular weight component of the above polyol were mixed in an amount shown in Table 1 so as to have an average molecular weight of 2000, and dried under reduced pressure at 70 ° C. for 12 hours. This was charged into a kolben, and 39.5 g of 4,4'-diphenylmethane diisocyanate was added to 100 parts by weight of the polyol, and reacted at 70 ° C. for 3 hours under a nitrogen atmosphere to synthesize a prepolymer.

Preparation of blade member and evaluation sample After defoaming the above prepolymer at 100 ° C. under reduced pressure, a mixture of 1,4-butanediol and trimethylolpropane (weight ratio = 75/25) was added to 100 parts by weight of the prepolymer. 6.62 g was added, and after mixing for 2 to 3 minutes, the mixture was charged into a mold rotating at 250 rpm in a centrifugal molding machine maintained at 140 ° C., and the rotation speed was increased to 1000 rpm to react for 60 minutes. A cylindrical sheet molded to a thickness of about 2 mm was taken out, cut and opened, after-cured at 120 ° C. for 12 hours, aged at room temperature for 7 days, and then cut to a predetermined size to obtain a blade member.

The same mixture as that charged into the mold of the centrifugal molding machine was poured into a mold for a rebound resilience measurement sample kept at 140 ° C., reacted for 60 minutes, demolded, and after-cured at 120 ° C. for 12 hours. After aging at room temperature for 7 days, a sample for rebound resilience measurement was obtained. In addition, three blade members are stacked (about 6 mm
Thickness) and a sample for hardness measurement.

Preparation of cleaning blade A dimer acid-based polyamide hot-melt adhesive is melt-coated with an applicator on the bonded portion of the phosphate-treated steel sheet, and the above-mentioned blade member is superimposed thereon. Was integrated with a supporting member to obtain a cleaning blade.

The blade member and the cleaning blade
Evaluation The blade member and the cleaning blade obtained as described above were evaluated as follows. 1) The rebound resilience is 5 ° C according to JIS-K6301.
The measurement was carried out after standing for 2 hours in an atmosphere of 25 ° C., 50 ° C. and 60 ° C. 2) JIS-A hardness was measured by a JIS-A spring hardness meter. 3) The chattering sound and the cleaning property of the cleaning blade are P-540 manufactured by Matsushita Electric Industrial Co., Ltd.
A. Attach the cleaning blade obtained above to a printer, and install 5 ° C. (× 30% RH) and 40 ° C. (× 80%
RH), and the presence or absence of chattering noise (squealing) and the cleaning property of up to 20,000 sheets were evaluated.
The results are shown in Table 1.

In the table, "PCL" represents polycaprolactone polyol. "PEA" stands for polyethylene adipate. "PBA" stands for polybutylene adipate. "PBHA" stands for polybutylenehexane adipate. "MDI" stands for 4,4'-diphenylmethane diisocyanate. "14BG / TMP"
Represents a 1,4-butanediol / trimethylolpropane mixture (75/25). In the evaluation of the cleaning blade, x indicates poor cleaning, and Δ indicates poor abrasion of the blade member edge.

Example 2 Synthesis of Polybutylene Adipate Ester As a synthesis of a polymer polyol, 3657 parts by weight of adipic acid and 2385 parts by weight of butylene glycol were charged.
A dehydration reaction was performed at 80 ° C. for 24 hours. The hydroxyl value of the obtained polyol was 22.3 KOHmg / g, and the acid value was 0.8.
KOH mg / g. The molecular weight was 5031. Next, as a synthesis of a low molecular weight polyol, 299 parts by weight of adipic acid and 275 parts by weight of butylene glycol were charged and a dehydration condensation reaction was performed at 180 ° C. for 5 hours. The hydroxyl value of the obtained polyol was 226 KOH mg / g, and the acid value was 0.4 KOH mg / g. The molecular weight was 496. In the same manner as in Example 1, the synthesis of the prepolymer, the preparation of the blade member and the evaluation sample, the preparation of the cleaning blade, and the evaluation thereof were performed. The results are shown in Table 1.

Example 3 Synthesis of Polybutylene Hexane Adipate As a synthesis of a polymer polyol, 3139 parts by weight of adipic acid, 1013 parts by weight of butylene glycol, and 1328 parts by weight of hexane glycol were charged, and a dehydration condensation reaction was performed at 180 ° C. for 20 hours. Was. The hydroxyl value of the obtained polyol was 24.4 KOHmg / g, and the acid value was 0.7 KOHmg / g.
g. The molecular weight was 4,600. Next, 336 parts by weight of adipic acid as a synthesis of a low molecular weight polyol,
149 parts by weight of butylene glycol and 195 parts by weight of hexane glycol were charged and a dehydration reaction was performed at 180 ° C. for 5 hours. The hydroxyl value of the obtained polyol is 189 KOHmg.
/ G, acid value was 0.5 KOHmg / g. The molecular weight was 593. In the same manner as in Example 1, the prepolymer was synthesized, the blade member and the evaluation sample were prepared, the cleaning blade was prepared, and the evaluation was performed.
It was shown to.

Example 4 Synthesis of Polycaprolactone Ester In a flask, 5890 parts by weight of ε-caprolactone, 62 parts by weight of ethylene glycol, and 0.1 part of tetrabutyl titanate were added.
And charged at 170 ° C. for 4 hours to give a hydroxyl value of 18.9 KOH mg / g and an acid value of 0.8 KOH mg / g.
g of polycaprolactone diol was obtained. According to the above formula, the molecular weight of this polyol was 5,937. Next, 465 parts by weight of ε-caprolactone, 62 parts by weight of ethylene glycol, and 0.01 part by weight of tetrabutyl titanate were similarly charged at 170 ° C.
For 4 hours to obtain polycaprolactone diol having a hydroxyl value of 213 KOH mg / g and an acid value of 0.5 KOH mg / g. The molecular weight was 527. In the same manner as in Example 1, the synthesis of the prepolymer, the preparation of the blade member and the evaluation sample, the preparation of the cleaning blade, and the evaluation thereof were performed. The results are shown in Table 1.

Comparative Example 1 As a polyol, polyethylene adipate "Nipporan 4040" (produced by Nippon Polyurethane Co., Ltd., hydroxyl value = 5)
6.0 KOH mg / g, acid value = 0.5 KOH mg / g,
(Molecular weight: 2004), the synthesis of a prepolymer, the production of a blade member and an evaluation sample, the production of a cleaning blade, and evaluation thereof were performed in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 As a polyol, polybutylene adipate "Nipporan 4010" (manufactured by Nippon Polyurethane Co., hydroxyl value = 5)
5.5 KOH mg / g, acid value = 0.4 KOH mg / g,
Using a molecular weight of 2022), the synthesis of a prepolymer, the preparation of a blade member and an evaluation sample, the preparation of a cleaning blade, and evaluation thereof were performed in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 3 As a polyol, polybutylenehexane adipate "OD-X-2108" (manufactured by Dainippon Ink and Chemicals, Inc.)
Hydroxyl value = 56.0KOHmg / g, Acid value = 0.4KO
Hmg / g, molecular weight: 2004), the synthesis of a prepolymer, the preparation of a blade member and an evaluation sample, the preparation of a cleaning blade, and the evaluation thereof were performed in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 4 Polycaprolactone polyol "Placcel 220" (manufactured by Daicel Chemical Industries, Ltd., hydroxyl value =
56.5 KOH mg / g, acid value = 0.5 KOH mg / g
g, molecular weight: 1986), and the synthesis of a prepolymer, the preparation of a blade member and an evaluation sample, the preparation of a cleaning blade, and evaluation thereof were performed in the same manner as in Example 1. The results are shown in Table 1.

[0035]

[Table 1]

[0036]

As described above, the cleaning blade for an electrophotographic apparatus of the present invention has the above-mentioned structure, and can control the rebound resilience of the electrophotographic apparatus in the temperature range of the apparatus to 75% or less. Has the property.

Claims (1)

(57) [Claims] 1. A blade member and a support member, an electrophotographic apparatus for a cleaning blade formed by joining through an adhesive layer, wherein the blade member has a molecular weight of 700 or less of the polyol
And a mixture of molecular weight 4500 or more polyols, Porii
After reacting with the cyanate, add a curing agent
A cleaning blade for an electrophotographic apparatus, characterized by comprising a polyurethane elastomer obtained by the conversion .